Metallurgical furnace



June 20, 1933. E. H. BUNCE ET AL 1,914,433

METALLURGICAL FURNACE Filed Jan. 23, 1930 3 Sheets-Sheet l ATTORN EY June 20, 1933. BUNCE r AL 1,914,483

METALLURGICAL FURNACE Filed Jan. 23. 1930 5 Sheets-Sheet 2 ATTORN EYS Patented June 20, 1933 UNITED STATES PATENT OFFICE EARL H. BUNCE, CLARENCE J. LENTZ AND GEORGE- T. MAHLER, 0F PALMERTON, PENN- SYLVANIA, ASSIGNORS TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y.,

.A CORPORATION OF NEW JERSEY METALLURGICAL FURNACE Application filed January 23, 1930. Serial No. 422,767.

This invention relates to metallurgical furnaces and has for its object certain improvements in metallurgical furnaces. The invention relates more particularly to metallurgical furnaces employed in the reduction of zinciferous materials.

Certain contaminating metals, such as lead, etc., are frequently associated with zinc ores. The metallurgy of zinc is lnade difiicult because of the persistence with which lead accompanies the zinc product. In copending application Serial No. 244.519, filed January 4, 1928, (which has since issued into United States Patent No. 1,749,127 of March 4, 1930) two of us, Bunce and Mahler, have disclosed and claimed a method of reducing zinciferous material containing lead. According to said copending application, the reduction process is more particularly practiced in a vertically disposed retort, the upper end of which extends well above the reduction furnace proper. This extension in fact constitutes a prolongation of the retort, and is generally referred to as an eliminator. A charge of zinciferous material and carbonaceous reducing agent inthe form of agglomerates is progressively passed downwardly through said eliminator and retort, the charge substantially filling both the eliminator and the retort. The retort is externally heated, and the heat necessary for reduction of the zinc compounds present in the agglomerated charge is gradually driven into and through the charge. The liberated zinc vapor rises and passes upwardly within the retort and the eliminator, as fresh agglomerates pass downwardly through the eliminator and retort. The agglomerates Within the eliminator act as a filter to the rising zinc vapor. Lead (and other contaminants, such as tin, antimony, bismuth, and germanium, as more particularly disclosed by two of us. Bunce and Mahler, in a copending application Serial No. 244,401, filed July 4, 1928) (which has since issued into United States Patent No. 1,749,126 of March 4, 1930) present in the Zinc vapor is selectively caught or retained by the hot agglomerates, with the result that substantially pure zinc vapor may be withdrawn from an exit provided in the eliminator. The zinc vapor is appropriately treated for the production of a merchantable product, such as zinc metal, zinc oxide or zinc dust.

\Vhile it has been amply demonstrated that the process above outlined is efiective in eliminating lead and the like from liberated zinc vapor and retort gases in the reduction of zinciferous materials, the question of providing a metallurgical furnace in which to practice the process is one that offers a number of serious diificulties. Two of us, Bunce and Mahler, have disclosed and claimed improvements in metallurgical furnaces in copending application, Serial No. 422,766, filed January 23, 1930, adapted for the practice of that process. The invention more particularly contemplated in that application relates to vertically disposed reduction retorts and eliminators placed above one another, so that their passageways are in substantial alignment with one another under operating conditions, the eliminator resting on or being supported by the retort. Thus, the eliminator and retort may comprise a unitary structure; the two devices denser or canister. The weight of the overhead eliminator, moreover, subjects the retort to an additional burden. Under such operating conditions, the retorts are more readily subject to failure or rupture.

As a result of our investigations, .we have determined that a metallurgical furnace may be constructed that overcomes in large part the objections just outlined with respect to eliminators resting on or supported by retorts, as well as with respect to integrally built retorts and eliminators. The new furnace avoids former difficulties encountered in bringing the furnace to heat, and in repairing ruptured retorts. Furthermore, the retorts of the new furnace are not as apt to fail or rupture. They are longer lived, and replacements are less frequent.

The present invention contemplates a metallurgical furnace comprising a reduction chamber, and an eliminator adjoining and communicating with said chamber, said eliminator being supported independently of the chamber when operativcly connected to the reduction chamber.

The novel features of the present invention, it is believed, will be better understood by reference to the accompanying drawings, taken in conjunction with the accompanying description, in which:

Fig. 1 is an elevation in section of a metallurgical furnace illustrative of the invention;

Fig. 2 is an enlarged section in part showing the construction of the connection between the retort and the eliminator of the apparatus shown in Fig. 1;

Fig. 3 is a transverse section on the line 3--3 of Fig. 2; and

Fig. 4 is an elevation in section of a modified arrangement of eliminator and retort in a metallurgical furnace of the. type shown in Fig. 1.

The metallurgical furnace shown comprises a furnace structure 10 resting on concrete foundations 11. A vertically disposed retort 12, preferably built up of appropriate heat resistant brick, rests within a heating chamber 13, The retort is supported only at its bottom, where it rests on the furnace structure. Its top is not tied into the furnace structure, and thus permits expansion and contraction independent of the surrounding furnace structure. The heating chamber is defined by heat resistant brick side walls 14. a brick bottom 15, and a brick arched roof 16. The brick linings of the furnace structure are surrounded by a metal casing 16'.

The retort extends completely through the furnace structure at both its upper and lower ends. An extension sleeve 17 is attached to the outside of the bottom of the furnace structure. Its passageway is in substantial alignment with the passageway of the retort. A revolving platform 18 is located immediately below the lower end of the retort. which is adapted for the removal of spent residues. This revolving platform may be operated intermittently, or continuously at regulated speeds; as desired.

The upper end of the retort protrudes a convenient distance above the top of the furnace structure, and preferably to a point eonveniently above a supporting platform 19 resting independently of the main furnace structure.

The heating chamber in which the retort rests may be heated in any desired manner. Thus, hot combustion gases may be supplied to the heating chamber by means of the burning of a suitable fuel, such as oil. gas or coal. On the other hand, the chamber and/or rctort may be heated by electrical energy. In the furnace illustrated. a port. or ports, 20. is shown for the introduction of oil or gas and air, which is combusted within the heating chamber. A number of these ports are advantagemlsly located in various parts of the furnace structure, extending completely through the side walls. An exit passageway 21 is provided at or near the upper end of the heating chamber for the withdrawal of combustion gases. This passageway preferably connects with a stack or chimney (not shown). A number of suitable openings are preferably provided through the furnace walls at various points in order to take pyrometric temperature measurements of the heating hamber. The space between the arch roof and the top of the furnace structure is filled with suitable heat-insulating material 22, such as diatomaceous earth or the like.

An eliminator structure 23 rests upon the supporting platform. It comprises a vertically disposed eliminator 24, with a passageway in substantial alignment with that of the retort. The eliminator itself is preferably constructed of suitable heat-resistant brick. An outer metallic casing 25 completely surrounds the eliminator. A suitable space is provided between the metallic casing and the eliminator for a layer of heat-insulating material 26, such as dust coal. The metallic casing itself is provided with a door, or doors. 27, for the removal of heat-insulating material, as desired. The thickness of the layer of heat-insulating material is of course in the first instance determined by the size of the metal casing. The upper end of the metallic casing is preferably open at or near its top for the introduction of the heat-insulating material. Various other means may of course be employed to regulate the temperature of the eliminator.

An off-take pipe 28, at or near the upper end of the eliminator, connects with a Zinc apor treatment device 29. If the zinc vapor is to be treated for the production of zinc metal, the device consists of a suitable condenser. On the other hand, if zinc oxide is to be manufactured, the device consists of an apparatus adapted to effect the oxidation of the zinc vapor. Thus, the device may consist of an apparatus adapted to direct a blast of oxidizing air against the stream of zinc vapor passed therethrough. If zinc dust is to be made, the device consists of a canister adaptiii) lit)

ed to effect the condensation of the zinc vapor into minute particles of zinc.

A charging device 30 extends downwardly within the eliminator to a point well below the inlet of the zinc vapor off-take pipe. This device is adapted to keep charge materials away from the entrance of the off-take pipe. A removable cap 31 rests over the opening or upper end of the eliminator. It may be removed from time to time for the introduction of fresh charge materials. If the apparatus is to be operated to effect continuous reduction of charge materials, the cap may be removed and a connection made to feed charg materials to the furnace substantially continuously.

If reference is made to Fig. 2, the connection between the retort and the eliminator may be more carefully considered. The upper end of the retort is provided with builtin L brick 32 adapted to telescope into the lower end of the eliminator. Pla n narrow brick set on end may be employed as a substitute for the L brick. The lower end of the eliminator. in case the passageways of the retort and eliminator are to be in substantial alignment, is provided with off-setting brick 33 adapted to fit around the outside of the L brick at the top of the retort. ()n the other hand. it will be clear that the passageway of the eliminator. for example, may be larger in cross section than that of the retort. Such an arrangement is particularly desirable, if it is desired bodily to raise the retort upwardly through and clear of the eliminator. If desired. moreover, the cross-section of the eliminator may be made smaller than that of the retort.

The eliminator structure is supported as follows: I-beams 34 appropriately spaced extend completely around the eliminator structure. A suitable number, for example, ten, of spaced cast iron saddles 35 are attached at their lower ends to the tops of the I-beams. These saddles are in turn adapted to hold a horizontally disposed cast iron supporting base member 36 extending completely around and below the eliminator structure. A sufficient amount of free space is provided between the L brick on the upper end of the retort and the cast iron base member to allow for the free expansion and contraction of the retort.without materially pushing against the eliminator. The metallic casing is held in position on the cast iron supporting member by means of guide angle irons 37 attached to the cast iron member.

If reference is now made to Fig. 3, the cast iron supporting member may be considered in more detail. It is provided with a number of internal passageways 38 running from one side to the other; such as by means of pipes imbedded in the body of the casting. These passageways are adapted for the passage of a cooling medium, such as Water or air, therethrough. Any convenient number of passageways may be provided, and various connections may be made suitably to pass the cooling medium therethrough.

Heat-insulating material 39 is provided between the I-beams and the retort. A metal plate 40 is attached to the I-beams and extends closely to the retort walls. This plate is adapted to support further amounts of heat-insulating material 41, which is preferably not put in place until the furnace has been brought to heat.

1f reference is now made to Fig. 4, a modified arrangement of apparatus may be considered. The eliminator structure 23 rests on or is supported by the retort structure 10. Thus, spaced I-beams 42 rest on the retort structure, which in turn support the eliminator structure resting on a base plate 43. I-beams 44 are attached to the base plate, which are adapted to keep the metallic casing 25 in place. In its other aspects, this apparatus is substantially like that shown in Fig. 1.

The above described a 'iparatus may advantageously be used as follows in the practice of the process outlined in the abovementioned copending applications for the reduction of zinciferous materials contaminated with objectionable amounts of lead and the like:

The cap 31 is removed, and an appropriately agglomerated charge of mixed zinciferous baterial and carbonaceous reducing agent is fed into and through the charging device 30. The agglomerates drop down through the passageways of the eliminator 24 and the retort 12 onto the revolving platform 18. The charging of the agglomerates is continued until both the retort and the eliminator are filled with the same.

The heating chamber 13 is suitably heated, such as by the combustion of gas fed through the ports 20. When sufficient heat has been driven through the retort walls and into the charge to effect the reduction of zinc compounds present in the agglomerates and the liberation of zinc vapor, a mixture consisting for the most part of zinc vapor and carbon monoxide rises upwardly, and gradually finds its way to the off-take pipe 28, through which it passes into the zinc vapor treatment device 29.

If the process is to be ope 'ated substantially continuously, the revolving platform 18 is made to revolve continuously, thus throwing off spent residues. The platform is made to revolve at a rate adapted to remove residues as fast as the reduction process proceeds to completion. Suitable amounts of charge materials are at the same time fed into the charging device 30. The cap may be removed from time to time for the insertion ot the charge materials, even though the reduction process itself takes place continuously.

On the other hand, the cap 31 may be permanently removed, and the charging device 30 may be placed in permanent connection with a source of charge materials, so that fresh agglomerates may be charged into the apparatus substantially as fast as spent residues are removed from the bottom of the retort.

\Vhen the liberated zinc vapor, contaminated with lead, wends its sinuous path upwardly through the retort and the eliminator, it necessarily contacts with hot agglomerates. Lead, or the like, present in the zinc vapor is selectively retained by the agglomerates. The lead-free zinc vapor ultimately passes through the tt'-take pipe .28 into the zinc treatment device. 29, where a relatively pure Zinc product may be made.

In order to effect the elimination of the lead present in the liberated zinc vapor, it is necessary to keep the agglomerates within the eliminator at a proper temperature. A. control of the eliminator temperature is obtained by suitably regulating the rate of heat dissipation from the eliminator. This control may be effected by regulating the amount of heat-insulating material surrounding the eliminator; as well as by regulating the amount of cooling medium, such as water, passed through the passageways 38 in the cast iron supporting member 36. Thus, more or less heat-insulating material 26 may be employed in the space provided between the metal casing 25 and the eliminator 24; and more or less water or air may be circulated through the passageways 38 in the cast iron supporting member 36.

Since the agglomerates within the eliminator are progressively. passed downwardly through the retort, the eliminating medium (i. e., the hot agglomerates) is constantly renewed, and fresh agglomerates are placed in the path of the rising zinc vapor which are adapted for the removal of further amounts of lead.

The lower end of the retort is advantageously not sealed to exclude seepage of air into the retort. In other words, it is better to have the lower end of the retort open, at least slightly, so that regulated amounts of air may be permitted to seep into the retort. It has been fouml that the reduction process may be materially aided by the admission of controlled amounts of air.

A consideration of the structural features of the apparatus described will readily indi cate that the eliminator, while. in communicative operation with the retort below, is supported entirely independentof the retort. It therefore follows that any expansion or movement of the retort cannot be translated to the eliminator. The telescoping joint provided between the retort and the eliminator makes this highly desirable result possible. In case the retort is to be repaired or replaced, the eliminator structure may be removed as a unit, whereby ready access is had to the retort; or, in case the passageway of the eliminator is larger in cross-section than that of the retort, the retort may be bodily lifted through and clear of the eliminator. In the case of the furnace more particularly shown in Fig. 1, it will also be noted that any expansion and movement of the retort structure cannot be translated to the eliminator structure, since the two are always out of contact with one another. It is thus seen that the metallurgical furnace of the present invention offers very superior structural ad vantages.

We claim:

1. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends, a vertically disposed eliminator resting directly above and communicating perpendicularly with said retort at its upper end, and a zinc treatment device in open communication with the elimi nator, said eliminator being separately supported from said retort, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

2. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends and surrounded by a heating chamber, a lead eliminator adjoining above and communicating perpendicularly with said retort at its upper end, and a zinc vapor treatment device in open communication with the eliminator, said eliminator being separately supported from said retort, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from Zinc vapor and retort gases passing from the retort through the eliminator.

3. A Zinc metallurgical furnace comprising a vertically disposed retort open at both ends and surrounded by a heating chamber, and an eliminator separately supported from said retort, the passageways of said retort and eliminator registering with one another under operating conditions, said eliminator and retort being operatively connected by means of an expansion joint, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

4. A zinc metallurgical furnace comprising a reduction chamber, a lead eliminator adjoining above and communicating perpendicularly with said chamber, and a zinc vapor treatment device in open communication with the eliminator, said eliminator being a unit separate and distinct from the reduction chamber, said eliminator being supported independently of the chamber and structure when operatively connected, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from Zinc vapor and retort gases passing from the chamber through the eliminator.

5. A zinc metallurgical furnace comprisa reduction chamber, a lead eliminator at oining above and communicating perpendicularly with said chamber, and a zinc vapor treatment device in open communication with the eliminator, said eliminator being supported independently of the chamber structure when operatively connected, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the chamber through the eliminator.

6. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends and confined within a furnace structure, a lead eliminator adjoining above and communicating perpendicularly with said retort, and a zinc vapor treatment device in open communication with the eliminator, said eliminator being a unit separate and distinctfrom the retort, said eliminator being sup orted independently of the retort and of tie furnace structure when operatively connected, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

7. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends and surrounded by a heating chamber defined by an outer furnace structure, and a vertically disposed eliminator adjoining and communicating with said retort, said eliminator being a unit separate and distinctfrom the retort, said eliminator being supported independently of the retort and of the furnace structure, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

8. A zinc metallurgical furnace comprising an upright reduction retort confined within a furnace structure adapted for the progressive passage of charge materials therethrough by the action of gravity, and an upright eliminator adjoining and communicating with said retort adapted for the progressive passage of an eliminating medium therethrough by the action of gravity, said eliminator being supported independ ently of the retort and of the furnace structure, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at atemperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

9. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends and confined within a furnace structure, and a vertically disposed eliminator open at both ends located above and communicating with said retort, said eliminator resting on a base member supported independently of the retort, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a ten'iperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

10. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends and confined within a furnace structure, a vertically disposed eliminator open at both ends located directly above and communicating perpemlicularly with said retort, and a zinc vapor treatment device in open communication with the eliminator, said eliminator resting on a base member provided with cooling means and supported independently of the retort, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator.

11. A zinc metallurgical furnace comprising a vertically disposed reduction retortopen at both ends and confined within a furnace structure. and a vertically disposed eliminator open at both ends located above and communicating with said retort, said eliminator being a unit separate and distinct from the retort, said eliminator likewise being provided with heat insulating material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc vapor and retort gases passing from the retort through the eliminator, said eliminator resting on a base member supported independently of the retort and of the furnace structure, said base member being provided with means for cooling the same.

12. A zinc metallurgical furnace comprising a vertically disposed reduction retort open at both ends and confined within a furnace structure, a vertically disposed eliminator open at both ends located directly above and communicating perpendicularly with said retort, and a zinc vapor treatment device in open communication with the eliminator, said eliminator being a unit separate and distinct from the retort, said eliminator likewise being provided with heat insulati'ng material to maintain the eliminator during operations at a temperature adapted selectively to remove impurities from zinc' vapor and retort gases passing from the reto t through the eliminator, said eliminator resting on a base member supported independently of the retort and of the furnace structure, said base member being provided with means for cooling the same including internal passageways for the transmission of a cooling medium therethrough.

13. A zinc metallurgical furnace comprising a vertically disposed reduction retort with an opening at or near its upper end for the introduction of charge materials and an opening at or near its lower end for the withdrawal of spent residues, a vertically disposed h at-insulated lead eliminating device above but unsupported by the retort, the passageways of the lead eliminating device and the retort being in open communication with one another so that a continuous column of charge materials may be progressively moved downwardly through both passageways simultaneously by the action of gravity, an opening at or near the upper end of the lead eliminating device for the introduction of fresh charge materials, a zinc vapor treatment device in association with the lead eliminating device, and a conduit connecting the upper section of the lead eliminating device with the zinc vapor treatment device.

14. A zinc metallurgical furnace according to the preceding claim, in which the lead eliminating device is supported by the furnace structure surrounding the retort.

15. A zinc metallurgical furnace according to claim 13, in which the upper end of the retort telescopes for a short distance into the lower end of the lead eliminator.

16. In a zinc metallurgical furnace, the combination comprising a reduction chamber with imperforate zinc vapor tight walls surrounded in large part by a fuel combustion chamber so that the walls of the reduction chamber may be heated externally, a lead eliminating chamber with imperforate zinc vapor tight walls positioned eXt-eriorly of said combustion chamber, the lead eliminating chamber and the reduction chamber being each independently supported and in open communication with one another so that both chambers may be filled with a continuous body of charge materials, and a Zincvapor treatment device in association with said eliminating chamber to receive lead-free zinc vapor therefrom.

17. A zinc metallurgical furnace comprising a reduction chamber with imperforate zinc vapor tight walls surrounded by an accompanying furnace structure, a lead eliminating chamber with imperforate zinc vapor tight walls and removed from and positioned exteriorly of the reduction chamber structure, the lead clizninator chamber and the reduction chamber being supported independently of one another the two chambers communicating with one another so that they may be tilled with a continuous column of charge materials, and a zinc-vapor treatment device in association with said lead.

eliminating chamber.

18. In a zinc metallurgical furnace, the combination comprising a vertically disposed reduction chamber with imperforate Zinc. vapor tight walls, a vertically disposed lead eliminating chamber with imperforate zinc vapor tight walls positioned directly above said reduction chamber, said chambers being in free and open communi-ation with one another so that a continuous body of charge materials may be "progressively passed by gravity therethrongh, said lead eliminating chamber and said reduction chamber being supported imlependently of one another, and a second zinc. vapor treatment device in association with said lead eliminating'chambcr.

In testimony whereof we ailix our signatures.

EARL ll. BUNCE. CLAHENPE J. LENTZ. GEORGE T. MAHLER.

CERTIFICATE OF CORRECTION.

Patent No. 1,914,483. June 20, 1933.

EARL H. BUNCE, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 99, for "'baterial" read "material"; page 4, line 87, claim 1, after "zinc" insert the word "vapor"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of August, A. D. 1933.

M J. Moore.

(Seal) Acting Commissioner of Patents. 

